Faraday polarization fluctuations associated with amplitude scintillations at Lunping

The diurnal, seasonal and solar cycle variations of Faraday polarization fluctuations (FPF) associated with amplitude scintillations observed at Lunping, Taiwan (25.0°N, 121.2°E : geographic) during the period 1978–1981 are presented. The occurrence of polarization fluctuations is maximum in the premidnight hours. FPFs occur either simultaneously or with a time lag after the onset of amplitude scintillations. There is an increase in FPF activity with an increase in sunspot activity. Occurrence of FPF peaks in the equinoxes. There had been a moderate activity in summer while the winter occurrence is a minimum. The seasonal occurrence pattern compared with reports from other locations indicates a longitudinal control on FPF activity. The maximum probable duration of FPF ranges from 15 to 30 min. It was found that the association of FPF with range spread-F is much better than that with frequency spread-F. Large ambient ionization densities corresponding to plasma frequencies greater than 15 MHz appear to create a favourable environment for the occurrence of FPF.     

Small-scale ionospheric structures associated with mid-latitude spread-F

Slant-F traces on ionograms recorded by a modern ionosonde in a sunspot-minimum period have revealed the existence of field-aligned irregularities at times of spread-F occurrence. This appears to be the first investigation in a mid-latitude region around 36° (geomagnetic) to detect these irregularities at F₂-region heights using an ionosonde. Although such traces were observed frequently near sunspot minimum they were seldom recorded for periods close to sunspot maximum. Also, for a specific spread-F event in August 1989, both the ionograms from the modern ionosonde and scintillations of 150 MHz transmissions from a Transit satellite indicate the existence in the ionosphere of periodic structures (period around 11 min). The scintillation recording also included rapidly fading signals indicative of small-scale structures. The satellite had a path close to the magnetic meridian which passed through the recording station (Brisbane, Australia). Because of the enhanced signal fluctuations in the scintillation recording on this occasion it seems likely (with the support of other evidence on the ionograms) that the small-scale structures present were field-aligned.     

Sudden neutral sodium layers: a strong link to sporadic E layers

A sodium LIDAR instrument located at Andenes, Norway (69°N; 16°E) observed several sudden developments of narrow sodium layers in the 90–100 km altitude region. These layers grow with typical time constants of 5 min and have a width of 1 km in altitude. We present the temporal and spatial properties for a number of these events. In a first step towards identifying the processes which create these layers we study the correlation of the growth phase of sudden sodium layers and of sporadic E layers. The latter have been recorded by an ionosonde located 129 km east of the LIDAR site. Within the mutual altitude and time resolution available in our common records a strong correlation of simultaneous occurrence of sudden sodium layers and E_s−l layers is observed, which establishes a strong link between the formation of the two types of layers. We further discuss processes which potentially could give rise to the formation of sudden sodium layers.     

Mid-latitude ionospheric scintillations of VHF radio signals associated with peculiar fluctuations of Faraday rotation

Simultaneous measurements of the scintillation and Faraday rotation of 136 MHz radio waves radiated by the Japanese geostationary satellite ETS-2 have been studied at Kokubunji Japan during April to May, 1977.These preliminary results show that there is a close association between scintillations and the peculiar fluctuations of the Faraday rotation due to ionospheric spread F, and an empirical formula relating them is presented.Furthermore, the successive daily values of the two parameters show a close correspondence with a cross correlation coefficient of about 0.8. An unexpected result is that cross-correlation between the incidence of Es and the Faraday fluctuations on a daily bases is found to be about 0.65.     

单檐歇山式古建筑抗震性能振动台试验

为有效保护古建筑,采用振动台试验方法,研究了中国明清官式木构古建的抗震性能。以故宫某单檐歇山木构古建为对象,制作了1∶2缩尺比例模型。模型含浮放柱底、柱架、斗拱、歇山屋顶、墙体等所有构造,且施工工艺完全符合中国明清官式木构古建施工规定。通过施加白噪声激励,获得了模型的基频和阻尼比。通过施加不同强度等级的1940年El-Centro波,获得了模型典型节点的位移和加速度响应,讨论了模型的减震系数,评价了浮放柱底、榫卯节点、斗拱、屋顶、墙体等构造的抗震性能。结果表明:模型的振动形式表现为平面内的扭摆,其原因与歇山式屋顶质量分布不均密切相关。模型的震前基频为1.47Hz,阻尼比为4.6%。地震作用下,模型的位移及加速度响应曲线近似稳定、均匀。尽管屋顶构造则对地震力有一定放大作用,但浮放柱底、榫卯节点、斗拱等构造能发挥较好的耗能减震作用。对于不同构造而言,榫卯节点的减震性能最好,其减震系数可降至0.30;斗拱次之,其减震系数可降至0.53;而浮放柱底与柱顶石之间的摩擦耗能性能最弱,其减震系数最小值为0.66。墙体在地震波强度增大过程中发生倒塌,但不影响结构整体稳定性。因此,单檐歇山式木构古建具有良好的抗震性能。     

Large carnivore attacks on hominins during the Pleistocene: a forensic approach with a Neanderthal example

Interaction between hominins and carnivores has been common and constant through human evolution and generated mutual pressures similar to those present in worldwide modern human-carnivore conflicts. This current interaction is sometimes violent and can be reflected in permanent skeletal pathologies and other bone modifications. In the present paper, we carry out a survey of 124 forensic cases of dangerous human-carnivore encounters. The objective is to infer direct hominin-carnivore confrontation during the Pleistocene, which is important to understand behavioral changes during human evolution. In addition, the case of Neanderthals is analyzed in order to find evidence of past attacks using forensic observations. The results obtained pose that Neanderthals could potentially have been involved in dangerous encounters during the Pleistocene, validating our methodology to approach past attacks from a forensic perspective.     

Pollen analysis of a soil sample associated with a Greek cult statue as a guide to provenance

A Classical Greek cult statue of a Goddess, “Aphrodite”, currently on display in the J. Paul Getty Museum has recently been reclaimed by the Italian government. The statue is thought to have been sculpted between 425 and 400 B.C. in southern Italy or Sicily, but its provenance is obscure. Soil incorporated into the true right arm socket of the acrolithic statue at the time of burial was pollen analyzed to provide information on its geographic origin. Since palynomorphs are often not well preserved in soils, a preliminary study was undertaken to investigate preservation and abundance of palynomorphs to determine the potential benefits of undertaking further analyses. Although concentration was low, the soil contained sufficient pollen and spores to determine the environment in the vicinity of the burial site of the statue. The landscape had been cleared of natural arboreal vegetation and intensively cultivated. Juglans regia and cereals were cultivated, and pastoralism may have been practiced. A specific geographic location could not be inferred without comparative soil analyses.     

Multicentric osteosarcoma associated with DISH,in a 19th century burial from England

Osteosarcoma is a rare type of malignant neoplasm that is most frequent in adolescents and young adults although it can develop at any age. It can metastasize from a primary site in bone to other bones and soft tissues. Usually the disorder causes a single bone‐forming lesion (unicentric) but some cases have multicentric, bone‐forming lesions. Some of these lesions develop at different sites at different times. In a second variant of multicentric osteosarcoma, synchronous bone‐forming lesions develop at multiple sites. Distinguishing between these two types of multicentric osteosarcoma is challenging in a clinical context and the criteria for doing so are unlikely to be met in an archaeological burial. Wolverhampton burial HB 39 was excavated from an early‐nineteenth century cemetery site in England. It consists of the incomplete skeleton of an adult male of at least 45 years of age with multicentric osteosarcoma. The individual represented by this burial also had diffuse idiopathic skeletal hyperostosis (DISH). Three of the bone‐forming lesions associated with osteosarcoma developed on the bony outgrowths related to DISH. Copyright © 2010 John Wiley & Sons, Ltd.     

Small scale irregularities associated with a high latitude electron density gradient: scintillation and EISCAT observations

A coordinated experiment involving scintillation observations using NNSS satellites and special program measurements with the EISCAT ionospheric radar facility is described. The results reveal the presence of sub-kilometre scale irregularities in the vicinity of a long lived steep equatorwards gradient in electron density. Evidence is presented of a southwards plasma flow which would cause the gradient to be unstable to the E Λ B gradient-drift mechanism. An instability growth time of about 4 min has been estimated from the observations. Cooler electron temperatures associated with enhanced densities rules out soft particle precipitation as an irregularity source in this case.     

Dendrochemical analysis of a tree-ring growth anomaly associated with the Late Bronze Age eruption of Thera

The most marked tree-ring growth anomaly in the Aegean dendrochronological record over the last 9000 years occurs in the mid 17th century BC, and has been speculatively correlated with the impact of the Late Bronze Age eruption of Thera (Santorini). If such a connection could be proved it would be of major interdisciplinary significance. It would open up the possibility of a precise date for a key archaeological, geological and environmental marker horizon, and offer a direct tie between tree-ring and ice-core records some 3600 years ago. A volcanic explanation for the anomaly is highly plausible, yet, in the absence of a scientifically proven causal connection, the value of the proposed correlation is limited. In order to test the hypothesis, dendrochemical analysis via Synchrotron Radiation Scanning X-ray Fluorescence Microscopy (SXFM), Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) was carried out on growth-ring series from four trees displaying the anomaly. Increases of sulfur, calcium, and rare earth elements following the onset of altered growth, plus concentration spikes of zinc and hafnium in the first affected growth-ring provide promising new evidence in support of a volcanic causal factor. Although a volcanic association is implied, the new data are not sufficient to prove a link to the exact eruption source.     

Geophysical signatures associated with fluid flow and gas hydrate occurrence in a tectonically quiescent sequence,Qiongdongnan Basin,South China Sea

Interpretation of high‐resolution two‐dimensional (2D) and three‐dimensional (3D) seismic data collected in the Qiongdongnan Basin, South China Sea reveals the presence of polygonal faults, pockmarks, gas chimneys and slope failure in strata of Pliocene and younger age. The gas chimneys are characterized by low‐amplitude reflections, acoustic turbidity and low P‐wave velocity indicating fluid expulsion pathways. Coherence time slices show that the polygonal faults are restricted to sediments with moderate‐amplitude, continuous reflections. Gas hydrates are identified in seismic data by the presence of bottom simulating reflectors (BSRs), which have high amplitude, reverse polarity and are subparallel to seafloor. Mud diapirism and mounded structures have variable geometry and a great diversity regarding the origin of the fluid and the parent beds. The gas chimneys, mud diapirism, polygonal faults and a seismic facies‐change facilitate the upward migration of thermogenic fluids from underlying sediments. Fluids can be temporarily trapped below the gas hydrate stability zone, but fluid advection may cause gas hydrate dissociation and affect the thickness of gas hydrate zone. The fluid accumulation leads to the generation of excess pore fluids that release along faults, forming pockmarks and mud volcanoes on the seafloor. These features are indicators of fluid flow in a tectonically‐quiescent sequence, Qiongdongnan Basin. Geofluids (2010) 10 , 351–368     

也谈义县奉国寺大雄殿大木尺度设计方法——与温玉清先生讨论

在近期公布的中国文化遗产研究院等单位关于辽宁义县奉国寺实测数据和研究成果的基础上,结合笔者对该寺木结构几何解析关系的认识和调研,本文尝试从斗栱设计、屋架结构设计和材分与营造尺配合等方面进行反思,逆向寻求和推算原始设计的方法。